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Valorization of Poly (ethylene) terephthalate (PET) wastes into magnetic carbon for adsorption of antibiotic from water: Characterization and application

Rai, Premanjali, Singh, Kunwar P.
Journal of environmental management 2018 v.207 pp. 249-261
Fourier transform infrared spectroscopy, Raman spectroscopy, X-radiation, X-ray diffraction, activated carbon, adsorbents, adsorption, bottles, carbon dioxide, cephalexin, energy, energy-dispersive X-ray analysis, ferrous oxide, magnetic materials, magnetism, nanocrystallites, nitrogen, physicochemical properties, polyethylene, polyethylene terephthalates, porous media, scanning electron microscopy, surface area, texture, thermogravimetry, transmission electron microscopy, wastes
Waste Polyethylene terephthalate (PET) bottles were pyrolyzed in the presence of nitrogen and converted into activated carbon (PETAC) by physical activation in carbon dioxide flow. An ex-situ precipitation and external reduction method were applied for the intercalation of ferromagnetic iron oxides onto the PETAC matrix. The characteristic structural and chemical properties of PETAC and magnetic PETAC (M-PETAC) were studied by Brunauer Emmett Teller (BET) surface area analysis, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FTIR) analysis, Raman spectroscopy, X-Ray Diffraction (XRD) analysis, Energy Dispersive analysis of X-rays (EDAX), Vibrating Sample Magnetometer (VSM), Thermal gravimetric analysis (TGA) and elemental analysis. Characterization results indicated that PETAC exhibited a relatively smooth and microporous texture with a surface area of 659.6 m²g⁻¹ while M-PETAC displayed a rugged morphology with a diminished surface area of 288.8 m²g⁻¹. XRD measurements confirmed the formation of iron oxide nanocrystallites with an average Scherrer crystallite size of 19.2 nm. M-PETAC delivered a quick response to an external magnet and exhibited saturation magnetization value of 35.4 emu g⁻¹. PETAC and M-PETAC were explored as potential adsorbents for the adsorption of a pharmaceutical (cephalexin) from water. Isotherm analysis revealed that M-PETAC exhibited a superior adsorption capacity (71.42 mg g⁻¹) compared to PETAC (21.27 mg g⁻¹). FTIR analysis of the adsorbents after CEX adsorption revealed the role of FeO as the nucleation site for enhanced adsorption of cephalexin by M-PETAC.